The great genome search continues...

This is a good time to be involved in genetics. Pretty much every day it seems new genetic variations are identified which are linked to one disease or another.

Ten years after the publication of the first human genome - the entire genetic code - scientists in every field of medical research are trawling the DNA of huge numbers of patients in order to see how they vary. These genome-wide association studies provide fresh insights into disease and human development.

Two studies published in the journal Nature Genetics look at Crohn's disease and female puberty. Both are international studies involving analysis of DNA from many thousands of individuals.

The Crohn's research project was the world's largest genetic study of inflammatory bowel disease involving 22,000 patients in 15 countries. The inflammatory gastrointestinal condition affects around 1 in 500 people in the UK.

The researchers identified 39 new gene variants associated with Crohn's, bring the total to 71. The means more genes are linked to Crohn's than any other disease. Those with the condition become ill with inflammation of the gastrointestinal tract which can cause pain, weight loss, vomiting and diarrhoea - many eventually require surgery to remove part of their gut.

About half the risk of Crohn's is genetic and half environmental, possibly involving a trigger from a viral infection. The research was led by Dr Miles Parkes a gastroenterologist at Cambridge University Hospitals. He said any of the genes identified might hold the key to beating Crohn's disease - via the development of new drug treatments.

The other study found 30 genes that play a part in controlling the age at which women reach puberty. The international group of scientists, including researchers at the Medical Research Council, found that many genes responsible for sexual maturity also play a role in how a woman's body metabolises fat. The researchers suggest this establishes new biological links between going through puberty at a young age and being at increased risk of obesity.

The study involved more than 100,000 women from Europe, the US and Australia. The lead author, Cathy Elks at the MRC Epidemiology Unit in Cambridge said:

"It is interesting that several of the new genes for puberty timing have been linked in other studies to body weight gain and obesity. This suggests that women in some families may inherit a joint genetic susceptibility to weight gain and early puberty."

BBC links

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